Background: We aimed to investigate the characteristics of pediatric ulcerative colitis (UC) at diagnosis in Korea. Methods: This was a multicenter, registry-based, inception cohort study conducted in Korea between 2021 and 2023. Children and adolescents newly diagnosed with UC < 18 years were included. Baseline clinicodemographics, results from laboratory, endoscopic exams, and Paris classification factors were collected, and associations between factors at diagnosis were investigated. Results: A total 205 patients with UC were included. Male-to-female ratio was 1.59:1, and the median age at diagnosis was 14.7 years (interquartile range 11.9–16.2). Disease extent of E1 comprised 12.2% (25/205), E2 24.9% (51/205), E3 11.2% (23/205), and E4 51.7% (106/205) of the patients. S1 comprised 13.7% (28/205) of the patients. The proportion of patients with a disease severity of S1 was significantly higher in patients with E4 compared to the other groups (E1: 0% vs. E2: 2% vs. E3: 0% vs. E4: 24.5%, P < 0.001). Significant differences between disease extent groups were also observed in Pediatric Ulcerative Colitis Activity Index (median 25 vs. 35 vs. 40 vs. 45, respectively, P < 0.001), hemoglobin (median 13.5 vs.13.2 vs. 11.6 vs. 11.4 g/dL, respectively, P < 0.001), platelet count (median 301 vs. 324 vs. 372 vs. 377 × 103 /μL, respectively, P = 0.001), C-reactive protein (median 0.05 vs. 0.10 vs. 0.17 vs. 0.38 mg/dL, respectively, P < 0.001), and Ulcerative Colitis Endoscopic Index of Severity (median 4 vs. 4 vs. 4 vs. 5, respectively, P = 0.006). No significant differences were observed in factors between groups divided according to sex and diagnosis age. Conclusion This study represents the largest multicenter pediatric inflammatory bowel disease cohort in Korea. Disease severity was associated with disease extent in pediatric patients with UC at diagnosis.

Background: We aimed to investigate the characteristics of pediatric ulcerative colitis (UC) at diagnosis in Korea. Methods: This was a multicenter, registry-based, inception cohort study conducted in Korea between 2021 and 2023. Children and adolescents newly diagnosed with UC < 18 years were included. Baseline clinicodemographics, results from laboratory, endoscopic exams, and Paris classification factors were collected, and associations between factors at diagnosis were investigated. Results: A total 205 patients with UC were included. Male-to-female ratio was 1.59:1, and the median age at diagnosis was 14.7 years (interquartile range 11.9–16.2). Disease extent of E1 comprised 12.2% (25/205), E2 24.9% (51/205), E3 11.2% (23/205), and E4 51.7% (106/205) of the patients. S1 comprised 13.7% (28/205) of the patients. The proportion of patients with a disease severity of S1 was significantly higher in patients with E4 compared to the other groups (E1: 0% vs. E2: 2% vs. E3: 0% vs. E4: 24.5%, P < 0.001). Significant differences between disease extent groups were also observed in Pediatric Ulcerative Colitis Activity Index (median 25 vs. 35 vs. 40 vs. 45, respectively, P < 0.001), hemoglobin (median 13.5 vs.13.2 vs. 11.6 vs. 11.4 g/dL, respectively, P < 0.001), platelet count (median 301 vs. 324 vs. 372 vs. 377 × 103 /μL, respectively, P = 0.001), C-reactive protein (median 0.05 vs. 0.10 vs. 0.17 vs. 0.38 mg/dL, respectively, P < 0.001), and Ulcerative Colitis Endoscopic Index of Severity (median 4 vs. 4 vs. 4 vs. 5, respectively, P = 0.006). No significant differences were observed in factors between groups divided according to sex and diagnosis age. Conclusion This study represents the largest multicenter pediatric inflammatory bowel disease cohort in Korea. Disease severity was associated with disease extent in pediatric patients with UC at diagnosis.

Background: We aimed to investigate the characteristics of pediatric ulcerative colitis (UC) at diagnosis in Korea. Methods: This was a multicenter, registry-based, inception cohort study conducted in Korea between 2021 and 2023. Children and adolescents newly diagnosed with UC < 18 years were included. Baseline clinicodemographics, results from laboratory, endoscopic exams, and Paris classification factors were collected, and associations between factors at diagnosis were investigated. Results: A total 205 patients with UC were included. Male-to-female ratio was 1.59:1, and the median age at diagnosis was 14.7 years (interquartile range 11.9–16.2). Disease extent of E1 comprised 12.2% (25/205), E2 24.9% (51/205), E3 11.2% (23/205), and E4 51.7% (106/205) of the patients. S1 comprised 13.7% (28/205) of the patients. The proportion of patients with a disease severity of S1 was significantly higher in patients with E4 compared to the other groups (E1: 0% vs. E2: 2% vs. E3: 0% vs. E4: 24.5%, P < 0.001). Significant differences between disease extent groups were also observed in Pediatric Ulcerative Colitis Activity Index (median 25 vs. 35 vs. 40 vs. 45, respectively, P < 0.001), hemoglobin (median 13.5 vs.13.2 vs. 11.6 vs. 11.4 g/dL, respectively, P < 0.001), platelet count (median 301 vs. 324 vs. 372 vs. 377 × 103 /μL, respectively, P = 0.001), C-reactive protein (median 0.05 vs. 0.10 vs. 0.17 vs. 0.38 mg/dL, respectively, P < 0.001), and Ulcerative Colitis Endoscopic Index of Severity (median 4 vs. 4 vs. 4 vs. 5, respectively, P = 0.006). No significant differences were observed in factors between groups divided according to sex and diagnosis age. Conclusion This study represents the largest multicenter pediatric inflammatory bowel disease cohort in Korea. Disease severity was associated with disease extent in pediatric patients with UC at diagnosis.

Background: We aimed to investigate the characteristics of pediatric ulcerative colitis (UC) at diagnosis in Korea. Methods: This was a multicenter, registry-based, inception cohort study conducted in Korea between 2021 and 2023. Children and adolescents newly diagnosed with UC < 18 years were included. Baseline clinicodemographics, results from laboratory, endoscopic exams, and Paris classification factors were collected, and associations between factors at diagnosis were investigated. Results: A total 205 patients with UC were included. Male-to-female ratio was 1.59:1, and the median age at diagnosis was 14.7 years (interquartile range 11.9–16.2). Disease extent of E1 comprised 12.2% (25/205), E2 24.9% (51/205), E3 11.2% (23/205), and E4 51.7% (106/205) of the patients. S1 comprised 13.7% (28/205) of the patients. The proportion of patients with a disease severity of S1 was significantly higher in patients with E4 compared to the other groups (E1: 0% vs. E2: 2% vs. E3: 0% vs. E4: 24.5%, P < 0.001). Significant differences between disease extent groups were also observed in Pediatric Ulcerative Colitis Activity Index (median 25 vs. 35 vs. 40 vs. 45, respectively, P < 0.001), hemoglobin (median 13.5 vs.13.2 vs. 11.6 vs. 11.4 g/dL, respectively, P < 0.001), platelet count (median 301 vs. 324 vs. 372 vs. 377 × 103 /μL, respectively, P = 0.001), C-reactive protein (median 0.05 vs. 0.10 vs. 0.17 vs. 0.38 mg/dL, respectively, P < 0.001), and Ulcerative Colitis Endoscopic Index of Severity (median 4 vs. 4 vs. 4 vs. 5, respectively, P = 0.006). No significant differences were observed in factors between groups divided according to sex and diagnosis age. Conclusion This study represents the largest multicenter pediatric inflammatory bowel disease cohort in Korea. Disease severity was associated with disease extent in pediatric patients with UC at diagnosis.

Objective: This case report was intended to report on a rare cause of spontaneous pneumomediastinum (SPM). Methods: When a patient with Crohn's disease (CD) visited our hospital for pneumomediastinum, a disease activity evaluation was performed, and specific questions were asked to identify possible causes of SPM. Results: The disease status of CD was confirmed as in active by evaluation. Specific questions about situations requiring the Valsalva maneuver, including vigorous exercise, lifting heavy objects, and difficult stool passage, were asked, but none were applicable. When asked an open question regarding incidents related to deep breathing, the patient answered that he had recently started smoking an electronic cigarette which required taking deep breaths. Conclusion Even when there is an underlying disease, specific history-taking is important if the possibility of complications related to the underlying disease is low. A new wave of previously unseen complications has emerged in parallel with increased electronic cigarette use.

Pyoderma gangrenosum is one of the dermatological extra-intestinal manifestations of ulcerative colitis (UC). We report a case of a 26-year-old male patient suffering from relapsed UC with a newly developed pyoderma gangrenosum. His skin and intestinal symptoms were intractable to treatment with steroids, immunosuppressants, or a single biological agent such as infliximab, golimumab, or vedolizumab. For the first time in Korea, we report a successful treatment experience of pyoderma gangrenosum in UC using dual biological agents, vedolizumab and infliximab. We strategically targeted each of the intestinal and skin symptoms, with a specific biological agent based on the drug’s mechanism of action.

Chronic recurrent multifocal osteomyelitis (CRMO) is an inflammatory bone disorder presenting with sterile osteomyelitis, most often presenting in childhood. Although the etiology is understood incompletely, its association with other auto-inflammatory diseases including inflammatory bowel disease (IBD); psoriasis; Wegener’s disease; arthritis; and synovitis, acne, pustulosis, hyperostosis, and osteitis (SAPHO) syndrome suggests that dysregulated innate immunity may play an important role in the pathogenesis. We report a case of a 13-year-old boy with CRMO associated with Crohn’s disease (CD) successfully treated with infliximab after failure of non-steroidal anti-inflammatory drug (NSAID) treatment. He initially was diagnosed with CRMO based on symmetric and aseptic bone lesions with no fever, lack of response to antibiotic treatment, vertebral involvement, and normal blood cell counts. Despite five months of NSAID treatment, his musculoskeletal symptoms were aggravated, and he developed gastrointestinal symptoms. Finally, he was diagnosed with CRMO associated with CD. Due to the severity of symptoms, infliximab was initiated and produced symptom improvement. This case supports infliximab as another choice for treatment of bowel symptoms in addition to the bone and joint symptoms of CRMO when other first-line treatments are ineffective.

Background/aims: The efficacy of biologics for the treatment of Crohn's disease (CD) is affected by the drug concentrations. We aimed to evaluate the importance of albumin and globulin which are known to be associated with drug concentrations as prognostic biomarkers in CD. Methods: In total, 121 pediatric patients with CD who had received anti-tumor necrosis factor (TNF)-α therapy were retrospectively examined between January 2010 and February 2019. Results: Relapse was observed in 48.8% of patients (59/121). The level of calprotectin (odds ratio, 2.13; p=0.03) and the albumin-to-globulin ratio (AGR) at 1 year after anti-TNF-α therapy (odds ratio, 0.0002; p=0.003) were associated with relapse. The AGR at 1 year after anti-TNF-α therapy was the only factor associated with the time-to-relapse (hazard ratio, 0.02; p<0.001). The optimal AGR cutoff value for the prediction of relapse was 1.47 (area under the curve, 0.916; p<0.001). The median infliximab trough level (TL) was lower in patients with AGRs <1.47 than in those with AGRs ≥1.47. Anti-drug antibody (ADA) concentrations were negatively correlated with the AGR at 1 year of anti-TNF-α therapy (r=-0.413, p=0.032). Conclusions AGR can be used to predict relapse. Patients with AGRs <1.47 at 1 year after anti-TNF-α therapy are more likely to have low drug TLs and develop ADAs, which increase the possibility of relapse than those with AGRs ≥1.47. Therefore, if the AGR at 1 year after anti-TNF-α therapy is less than 1.47, clinicians should monitor disease activity, assess the TLs of the anti-TNF-α agents, test for ADAs and determine the appropriate therapeutic strategies.

Background/Aims: Although mucosal healing (MH) is acknowledged as the treatment target in the treat-to-target era, there are limitations on repeated endoscopic examinations, especially in pediatric patients. We aimed to investigate whether fecal calprotectin (FC) could serve as a surrogate marker for the assessment of MH in pediatric patients with Crohn’s disease (CD) who have achieved sustained clinical remission (CR) while treated with anti-tumor necrosis factor (TNF) agents. Methods: This multicenter retrospective cross-sectional study included pediatric CD patients who had sustained a CR for at least 6 months with anti-TNF agents and who simultaneously underwent ileocolonoscopy and FC tests during follow-up. MH was defined as the absence of any ulcer on ileocolonoscopy. Results: A total of 131 patients were included in this study. MH was observed in 87 patients (66.7%). The FC level was significantly lower in patients with MH than in those without MH (median 49.0 mg/kg vs 599.0 mg/kg; p<0.001). According to the multivariate logistic regression analysis, FC was the only factor associated with MH (odds ratio, 0.62; 95% confidence interval [CI], 0.52 to 0.73; p<0.001). According to the receiver operating characteristic curve analysis, the optimal cutoff value for FC for the association with MH was <140 mg/kg (area under the curve 0.890, 95% CI 0.829 to 0.951, sensitivity 78.2%, specificity 88.6%, p<0.001). Conclusions FC was associated with MH in pediatric patients with CD who had achieved a sustained CR for at least 6 months with anti-TNF agents. In these patients, FC can be used to stratify patients and guide decisions regarding ileocolonoscopy in the treat-to-target era.

Background/Aims: We aimed to compare the differences in pediatric Crohn’s disease (CD) and ulcerative colitis (UC) at diagnosis in Korea. Methods: This was a multicenter, registry-based, inception cohort study conducted at five centers in Korea between 2013 and 2017. Baseline demographics, clinical characteristics, and results from laboratory, endoscopic, radiologic examinations were compared between pediatric CD and UC patients who were <19 years old at diagnosis. Results: A total 307 patients were included (227 CD [73.9%] and 80 UC [26.1%]). The male to female ratio was 2.49:1 for CD, and 1.49:1 for UC (p=0.019). Median age at diagnosis was 14.4 years (interquartile range, 12.4 to 16.2) for CD, and 14.4 years (interquartile range, 11.7 to 16.5) for UC (p=0.962). Hematochezia was the only dominant symptom in UC patients compared to CD patients (86.2% vs 30.8%, p<0.001). White blood cell counts, platelet counts, erythrocyte sedimentation rate, and C-reactive protein levels were significantly higher, and serum albumin level was significantly lower in CD patients than in UC patient. Anti-Saccharomyces cerevisiae antibody was positive in 44.5% and 16.2% of CD and UC patients, respectively (p<0.001), and antineutrophil cytoplasmic antibody was positive in 15.0% and 58.8% of CD and UC patients, respectively (p<0.001). Terminal ileal involvement was prominent in CD, while rectal involvement was more prominent in UC. Small bowel involvement and perianal perforating diseases were also more prominent in CD. Conclusions This is the first a multicenter study in Korea to compare the differences between pediatric CD and UC at diagnosis in Korea. A large-scale, national study is expected to better clarify these findings in the future.